Fin-and-Tube Heat Exchanger Solid Core Advanced Simulation

This paper is devoted to the presentation of an advanced model for the heat conduction processes within a finned tube bundle, typically found in air-cooled evaporators and condensers. As a result of the computational effort needed to simulate the desired fin-and-tube local unsteadiness, some actions have been undertaken in order to obtain reasonable simulation time consumption. A specific cutting cell grid has been proposed for the fins to adapt to the tubes shape, reducing strongly the grid density comparing to alternative methods such as the blocking-off. Additionally, a specific numerical procedure has been formulated to maintain the matrix of coefficients constant, allowing the use of direct solvers for the system of equations. Another important aspect of the current approach is the angular discretisation of the tubes, oriented to take into account angular variations of in-tube heat transfer coefficients (as in stratified flow, typical of liquid overfeed evaporators). Verification studies are presented based on MMS methodology. Some illustrative results are also presented regarding transient simulations of finned tube evaporators and an initial study of the influence of in-tube heat transfer coefficient asymmetry.